Thursday, April 22, 1999 Published at 13:38 GMT 14:38 UKWorld: AmericasKillers' parents pray for victimsTributes to the shooting victims are left in a snowy park by the schoolThe parents of the Colorado school killers have expressed their "heartfelt sympathy" to the victims of the massacre and their families.

The families of Eric Harris, 18, and Dylan Klebold, 17, issued separate statements as police investigated whether their sons had had accomplices in their devastating rampage through Columbine High School, in which 13 people were killed.

"Our thoughts, prayers and heartfelt apologies go out to the victims, their families, friends, and the entire community," the Klebold family said.

"There was a lot of planning put into this. It took a considerable amount of time to make it," said Sheriff Stone.

The county's prosecutor, Dave Thomas, said: "There is some belief that there are other people at least knowledgeable about this."

Police question a pupil believed to be a friend of the suspects

Police have taken books and computer equipment from the homes of the two suspects to try to determine whether anyone else helped them with the massacre.

Three people, believed to be friends of the suspects, were arrested in a field near the school and led away in handcuffs.

A police spokeswoman said they were wanted for questioning and were not thought to be directly responsible for the shootings.

Shrine for the dead

Pupils help their wounded classmates

The bodies of the 13 dead were finally removed from the school on Wednesday evening - more than 24 hours after they were killed. The remains of the two teenage gunmen were also removed.

Throughout Wednesday, pupils wearing blue and silver ribbons, the colours of Columbine High School, returned in tears and clung on to each other as they laid flowers at two shrines.

It was the worst massacre in a string of school shootings that have rocked US communities in recent years.

Calls for gun control

The shootings have once again prompted calls for tighter gun control.

Colorado legislators have responded by withdrawing a plan to permit possession of concealed firearms, and the most powerful gun lobbying organisation in America, the National Rifle Association, has decided to scale back its annual conference in Denver next week.

US President Bill Clinton used a speech to White House volunteers on Wednesday to express national shock at the tragedy.

"We have to take this moment once again to hammer home to all the children of America that violence is wrong, and to show children by the power of our own example how to resolve conflicts peacefully," he said